Example: Handling connection exceptions for BMP beans in container-managed database transactions

The following code sample demonstrates how to roll back transactions and issue exceptions to the bean client in cases of stale connection exceptions.

//===================START_PROLOG======================================

//

//   5630-A23, 5630-A22, 
//   (C) COPYRIGHT International Business Machines Corp. 2005,2008

//   All Rights Reserved

//   Licensed Materials - Property of IBM

//   disclosure restricted by GSA ADP Schedule Contract with IBM Corp.

//

//   IBM DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING

//   ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

//   PURPOSE. IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL, INDIRECT OR

//   CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF

//   USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR

//   OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE

//   OR PERFORMANCE OF THIS SOFTWARE.

//

//===================END_PROLOG========================================
 package WebSphereSamples.ConnPool;
 import java.util.*;
 import javax.ejb.*;
 import java.sql.*;
 import javax.sql.*;
 import javax.ejb.*;
 import javax.naming.*;
 import com.ibm.websphere.rsadapter.WSCallHelper;

/**
 * This is an Entity Bean class with five BMP fields
 * String firstName, String lastName, String middleInit
 * String empNo, int edLevel
 */ public class EmployeeBMPBean implements EntityBean {
       private javax.ejb.EntityContext entityContext = null;
       final static long serialVersionUID = 3206093459760846163L;

       private java.lang.String firstName;
       private java.lang.String lastName;
       private String middleInit;
       private javax.sql.DataSource ds;
       private java.lang.String empNo;
       private int edLevel;
/**
 * ejbActivate method 
 * ejbActivate calls getDS(), which performs the 
 * JNDI lookup for the datasource.
 */ public void ejbActivate() {
       getDS();
}
/**
 * ejbCreate method for a BMP entity bean
 * @return WebSphereSamples.ConnPool.EmployeeBMPKey
 * @param key WebSphereSamples.ConnPool.EmployeeBMPKey
 * @exception javax.ejb.CreateException 
 */ 
public WebSphereSamples.ConnPool.EmployeeBMPKey ejbCreate(String empNo,  String firstName, String lastName, String middleInit, int edLevel) throws  javax.ejb.CreateException {

   Connection conn = null;
   PreparedStatement ps = null;
       
   if (ds == null) getDS();
              
   this.empNo = empNo;
   this.firstName = firstName;
   this.lastName = lastName;
   this.middleInit = middleInit;
   this.edLevel = edLevel;

   String sql = "insert into Employee (empNo, firstnme, midinit, lastname,         edlevel) values (?,?,?,?,?)";
              
   try {
      conn = ds.getConnection();
      ps = conn.prepareStatement(sql);                     
      ps.setString(1, empNo);
      ps.setString(2, firstName);
      ps.setString(3, middleInit);
      ps.setString(4, lastName);
      ps.setInt(5, edLevel);
              
 if (ps.executeUpdate() != 1){
         System.out.println("ejbCreate Failed to add user.");
         throw new CreateException("Failed to add user.");
      }
   } 
   catch (SQLException se)
   {
      if (WSCallHelper.getDataStoreHelper(ds).isConnectionError(se))
      {
         
// This exception indicates that the connection to the database is no longer valid.
         
// Rollback the transaction, and throw an exception to the client indicating they
         
// can retry the transaction if desired.

         System.out.println("Connection is stale: " +  se.getMessage());
         throw new CreateException(se.getMessage());
      } 
      else
      {
         System.out.println("SQL Exception during get connection or process SQL: " +
                          se.getMessage());
         throw new CreateException(se.getMessage());
      } 


    finally
   {
      
// Always close the connection in a finally statement to ensure proper 
      
// closure in all cases. Closing the connection does not close an
      
// actual connection, but releases it back to the pool for reuse.
      if (ps != null)
      {
         try
         {
            ps.close();
         } 
         catch (Exception e)
         {
            System.out.println("Close Statement Exception: " + e.getMessage());
         }
      }
      if (conn != null)
      {
         try
         {
            conn.close();
         } 
         catch (Exception e)
         {
            System.out.println("Close connection exception: " + e.getMessage());
         }
      }


    return new EmployeeBMPKey(this.empNo);
}
/**
 * ejbFindByPrimaryKey method
 * @return WebSphereSamples.ConnPool.EmployeeBMPKey
 * @param primaryKey WebSphereSamples.ConnPool.EmployeeBMPKey
 * @exception javax.ejb.FinderException
 */ public WebSphereSamples.ConnPool.EmployeeBMPKey
     ejbFindByPrimaryKey(WebSphereSamples.ConnPool.EmployeeBMPKey primaryKey)
                 javax.ejb.FinderException {
       loadByEmpNo(primaryKey.empNo);
       return primaryKey;
}
/**
 * ejbLoad method
 */ public void ejbLoad() {
       try {
              EmployeeBMPKey pk = (EmployeeBMPKey) entityContext.getPrimaryKey();
              loadByEmpNo(pk.empNo);
       } catch (FinderException fe) {
              throw new EJBException("Cannot load Employee state from database.");
       }       
}
/**
 * ejbPassivate method
 */ public void ejbPassivate() {}
/**
 * ejbPostCreate method for a BMP entity bean
 * @param key WebSphereSamples.ConnPool.EmployeeBMPKey
 */ public void ejbPostCreate(String empNo, String firstName, String lastName, String middleInit,     int edLevel) {}
/**
 * ejbRemove method
 * @exception javax.ejb.RemoveException
 */ 
public void ejbRemove() throws javax.ejb.RemoveException
{
       
   if (ds == null) 
      GetDS();

   String sql = "delete from Employee where empNo=?";
   Connection con = null;
   PreparedStatement ps = null;
   try
   {                     
      con = ds.getConnection();                                                               
      ps = con.prepareStatement(sql);                                          
      ps.setString(1, empNo);
      if (ps.executeUpdate() != 1)
      {
         throw new EJBException("Cannot remove employee: " + empNo);
      }
   } 
   catch (SQLException se)
   {
      if (WSCallHelper.getDataStoreHelper(ds).isConnectionError(se))
      {
         
// This exception indicates that the connection to the database is no longer valid.
         
// Rollback the transaction, and throw an exception to the client indicating they
         
// can retry the transaction if desired.

         System.out.println("Connection is stale: " + se.getMessage());
         throw new EJBException(se.getMessage());
      } 
      else
      {
         System.out.println("SQL Exception during get connection or process SQL: " +
                          se.getMessage());
         throw new EJBException(se.getMessage());   
      } 


    finally
   {
      
// Always close the connection in a finally statement to ensure proper 
      
// closure in all cases. Closing the connection does not close an
      
// actual connection, but releases it back to the pool for reuse.
      if (ps != null)
      {
         try
         {
            ps.close();
         } 
         catch (Exception e)
         {
            System.out.println("Close Statement Exception: " + e.getMessage());
         }
      }
      if (con != null)
      {
         try
         {
            con.close();
         } 
         catch (Exception e)
         {
            System.out.println("Close connection exception: " + e.getMessage());
         }
      }


 }
/**
 * Get the employee's edLevel
 * Creation date: (4/20/2001 3:46:22 PM)
 * @return int
 */ 
public int getEdLevel() {
       return edLevel;
}
/**
 * getEntityContext method
 * @return javax.ejb.EntityContext
 */ 
public javax.ejb.EntityContext getEntityContext() {
       return entityContext;
}
/**
 * Get the employee's first name
 * Creation date: (4/19/2001 1:34:47 PM)
 * @return java.lang.String
 */ 
public java.lang.String getFirstName() {
       return firstName;
}
/**
 * Get the employee's last name
 * Creation date: (4/19/2001 1:35:41 PM)
 * @return java.lang.String
 */ 
public java.lang.String getLastName() {
       return lastName;
}
/**
* get the employee's middle initial
 * Creation date: (4/19/2001 1:36:15 PM)
 * @return char
 */ 
public String getMiddleInit() {
       return middleInit;
}
/**
 * Lookup the DataSource from JNDI
 * Creation date: (4/19/2001 3:28:15 PM)
 */ 
private void getDS() {
       try {
              Hashtable parms = new Hashtable();
              parms.put(Context.INITIAL_CONTEXT_FACTORY, 
                            "com.ibm.websphere.naming.WsnInitialContextFactory");
              InitialContext ctx = new InitialContext(parms);
              
// Perform a naming service lookup to get the DataSource object.
              ds = (DataSource)ctx.lookup("java:comp/env/jdbc/SampleDB");
       } 
       catch (Exception e) {
              System.out.println("Naming service exception: " + e.getMessage());
              e.printStackTrace();
       }
}
/**
 * Load the employee from the database
 * Creation date: (4/19/2001 3:44:07 PM)
 * @param empNo java.lang.String
 */ 
private void loadByEmpNo(String empNoKey) throws javax.ejb.FinderException
{
       String sql = "select empno, firstnme, midinit, lastname, edLevel from employee where empno = ?";
       Connection conn = null;
       PreparedStatement ps = null;
       ResultSet rs = null;

       if (ds == null) getDS();
       
       try
       {
              
// Get a Connection object conn using the DataSource factory.
              conn = ds.getConnection();
              
// Run DB query using standard JDBC coding.
              ps = conn.prepareStatement(sql);
              ps.setString(1, empNoKey);
              rs = ps.executeQuery();
              if (rs.next())
              {
                     empNo= rs.getString(1);
                     firstName=rs.getString(2);
                     middleInit=rs.getString(3);
                     lastName=rs.getString(4); 
                     edLevel=rs.getInt(5);
              } 
              else
              {
                throw new ObjectNotFoundException("Cannot find employee number " +
                                                   empNoKey);
              }
       } 
       catch (SQLException se)
       {
         if (WSCallHelper.getDataStoreHelper(ds).isConnectionError(se))
         {
           
// This exception indicates that the connection to the database is no longer valid.
           
// Roll back the transaction, and throw an exception to the client indicating they
           
// can retry the transaction if desired.

           System.out.println("Connection is stale: " + se.getMessage());
           throw new FinderException(se.getMessage());
         } 
         else
         {
           System.out.println("SQL Exception during get connection or process SQL: " +
                               se.getMessage());
           throw new FinderException(se.getMessage());
         } 
       }
       finally
       {
         
// Always close the connection in a finally statement to ensure 
         
// proper closure in all cases. Closing the connection does not 
         
// close an actual connection, but releases it back to the pool 
         
// for reuse.
         if (rs != null)
         {
            try
            {
               rs.close();
            } 
            catch (Exception e)
            {
               System.out.println("Close Resultset Exception: " + e.getMessage());
            }
         }
         if (ps != null)
         {
            try
            {
               ps.close();
            } 
            catch (Exception e)
            {
               System.out.println("Close Statement Exception: " + e.getMessage());
            }
         }
         if (conn != null)
         {
            try
            {
               conn.close();
            } 
            catch (Exception e) 
            {
               System.out.println("Close connection exception: " + e.getMessage());
            }
         }
       }      
}
/**
 * set the employee's education level
 * Creation date: (4/20/2001 3:46:22 PM)
 * @param newEdLevel int
 */ 
public void setEdLevel(int newEdLevel) {
       edLevel = newEdLevel;
}
/**
 * setEntityContext method
 * @param ctx javax.ejb.EntityContext
 */ 
public void setEntityContext(javax.ejb.EntityContext ctx) {
       entityContext = ctx;
}
/**
 * set the employee's first name
 * Creation date: (4/19/2001 1:34:47 PM)
 * @param newFirstName java.lang.String
 */ 
public void setFirstName(java.lang.String newFirstName) {
       firstName = newFirstName;
}
/**
 * set the employee's last name
 * Creation date: (4/19/2001 1:35:41 PM)
 * @param newLastName java.lang.String
 */ 
public void setLastName(java.lang.String newLastName) {
       lastName = newLastName;
}
/**
 * set the employee's middle initial
 * Creation date: (4/19/2001 1:36:15 PM)
 * @param newMiddleInit char
 */ 
public void setMiddleInit(String newMiddleInit) {
       middleInit = newMiddleInit;
}
/**
 * unsetEntityContext method
 */ 
public void unsetEntityContext() {
       entityContext = null;
}
}

//===================START_PROLOG======================================

//

//   5630-A23, 5630-A22, 
//   (C) COPYRIGHT International Business Machines Corp. 2002,2008

//   All Rights Reserved

//   Licensed Materials - Property of IBM

//   disclosure restricted by GSA ADP Schedule Contract with IBM Corp.

//

//   IBM DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING

//   ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

//   PURPOSE. IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL, INDIRECT OR

//   CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF

//   USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR

//   OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE

//   OR PERFORMANCE OF THIS SOFTWARE.

//

//===================END_PROLOG========================================
 package WebSphereSamples.ConnPool;

/**
 * This is an Enterprise Java Bean Remote Interface
 */ public interface EmployeeBMP extends javax.ejb.EJBObject {

/**
 * 
 * @return int
  */ int getEdLevel() throws java.rmi.RemoteException;
/**
 * 
 * @return java.lang.String
 */ java.lang.String getFirstName() throws java.rmi.RemoteException;
/**
 * 
 * @return java.lang.String
 */ java.lang.String getLastName() throws java.rmi.RemoteException;
/**
 * 
 * @return java.lang.String
 */ java.lang.String getMiddleInit() throws java.rmi.RemoteException;
/**
 * 
 * @return void
 * @param newEdLevel int
 */ void setEdLevel(int newEdLevel) throws java.rmi.RemoteException;
/**
 * 
 * @return void
 * @param newFirstName java.lang.String
 */ void setFirstName(java.lang.String newFirstName) throws java.rmi.RemoteException;
/**
 * 
 * @return void
 * @param newLastName java.lang.String
 */ void setLastName(java.lang.String newLastName) throws java.rmi.RemoteException;
/**
 * 
 * @return void
 * @param newMiddleInit java.lang.String
 */ void setMiddleInit(java.lang.String newMiddleInit) throws java.rmi.RemoteException;
}

//===================START_PROLOG======================================

//

//   5630-A23, 5630-A22, 
//   (C) COPYRIGHT International Business Machines Corp. 2002,2008

//   All Rights Reserved

//   Licensed Materials - Property of IBM

//   disclosure restricted by GSA ADP Schedule Contract with IBM Corp.

//

//   IBM DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING

//   ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

//   PURPOSE. IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL, INDIRECT OR

//   CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF

//   USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR

//   OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE

//   OR PERFORMANCE OF THIS SOFTWARE.

//

//===================END_PROLOG========================================
 package WebSphereSamples.ConnPool;

/**
 * This is an Enterprise Java Bean Remote Interface
 */ public interface EmployeeBMP extends javax.ejb.EJBObject {

/**
 * 
 * @return int
  */ int getEdLevel() throws java.rmi.RemoteException;
/**
 * 
 * @return java.lang.String
 */ java.lang.String getFirstName() throws java.rmi.RemoteException;
/**
 * 
 * @return java.lang.String
 */ java.lang.String getLastName() throws java.rmi.RemoteException;
/**
 * 
 * @return java.lang.String
 */ java.lang.String getMiddleInit() throws java.rmi.RemoteException;
/**
 * 
 * @return void
 * @param newEdLevel int
 */ void setEdLevel(int newEdLevel) throws java.rmi.RemoteException;
/**
 * 
 * @return void
 * @param newFirstName java.lang.String
 */ void setFirstName(java.lang.String newFirstName) throws java.rmi.RemoteException;
/**
 * 
 * @return void
 * @param newLastName java.lang.String
 */ void setLastName(java.lang.String newLastName) throws java.rmi.RemoteException;
/**
 * 
 * @return void
 * @param newMiddleInit java.lang.String
 */ void setMiddleInit(java.lang.String newMiddleInit) throws java.rmi.RemoteException;
}

//===================START_PROLOG======================================

//

//   5630-A23, 5630-A22, 
//   (C) COPYRIGHT International Business Machines Corp. 2002,2008

//   All Rights Reserved

//   Licensed Materials - Property of IBM

//   disclosure restricted by GSA ADP Schedule Contract with IBM Corp.

//

//   IBM DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING

//   ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

//   PURPOSE. IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL, INDIRECT OR

//   CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF

//   USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR

//   OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE

//   OR PERFORMANCE OF THIS SOFTWARE.

//

//===================END_PROLOG========================================
 package WebSphereSamples.ConnPool;

/**
* This is a Primary Key Class for the Entity Bean
**/ 
public class EmployeeBMPKey implements java.io.Serializable { 
     public String empNo;
     final static long serialVersionUID = 3206093459760846163L;

/**
* EmployeeBMPKey() constructor 
*/ public EmployeeBMPKey()  {
}
/**
* EmployeeBMPKey(String key) constructor 
*/ 
public EmployeeBMPKey(String key)  {
     empNo = key;
}
/**
* equals method
* - user must provide a proper implementation for the equal method. The generated 
*   method assumes the key is a String object.
*/ 
public boolean equals (Object o)  {
     if (o instanceof EmployeeBMPKey) 
          return empNo.equals(((EmployeeBMPKey)o).empNo);
     else
          return false;
}
/**
* hashCode method
* - user must provide a proper implementation for the hashCode method. The generated
*    method assumes the key is a String object.
*/ 
public int hashCode ()  {
     return empNo.hashCode();

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Example: Handling connection exceptions for BMP beans in container-managed database transactions

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